Thermally assisted recording is a scheme whereby data is recorded on a magnetic disk by applying heat at not lower than 200° C., together with a magnetic field, to a recording bit region of the order of several tens of nm in diameter, on the magnetic disk. Hopes run high that the thermally assisted recording is a recording scheme capable of high-density magnetic recording. As means for causing an instantaneous increase in temperature of a minute recording bit region on a magnetic disk, use of an optical near-field is under study at present. For generation of the optical near-field, it is necessary to introduce light into an optical near-field transducer disposed in the vicinity of a recording pole of a magnetic head. Use of a laser diode (hereinafter referred to as an LD) as a light source for such a purpose is under study, however, an LD being a heat source as well as the light source, the LD has a problem in that oscillation output thereof undergoes deterioration, due to heat evolution of the LD itself. An LD for use in an optical disk recorder normally stops oscillation at 70° C. or higher.
In Patent Document 1, there has been disclosed a thermally assisted magnetic recording head wherein means for prevention of warming are disposed in the vicinity of a light source (heat source) disposed in close proximity of a write element to thereby avoid output deterioration due to heat evolution caused by the light source (heat source) itself. More specifically, four different means for prevention of warming are proposed as follows; (1) to provide a heat sink member in contact with a light source, (2) to carry out forced air-cooling with the use of a piezoelectric bimorph fan, (3) to devise a slider in such an unique shape as to guide a portion of an air flow passing by the slider to a light source to thereby effect air-cooling, and (4) to bring a slider into contact with a disk to thereby cause heat release toward the disk.
Further, in Non-patent Document 1, it has been described that an optical system comprising a light source, an incident light detector, a reflected light detector, a beam splitter, a lens, and a half-wave plate is disposed outside a slider, and a grating formed at the head part of a slider is irradiated with light from the optical system to thereby guide the light to a magnetic write element accompanying the slider, whereupon an optical near-field is generated by an optical near-field transducer to thereby heat a minute region on a disk, opposite to the slider, with an extremely minute interval provided therebetween.    [Patent Document 1] JP-A No. 2001-283403    [Non-patent Document 1] “Integration Challenge for Heat Assisted Magnetic Recording” by Ed. Gage, IDMA JAPAN International Forum 2006, Jun. 9, 2006